Safety device for molding machine

ABSTRACT

A safety device for a machine mechanism having relatively movable pressure applying operating portions such as a molding machine having relatively movable mold platens, with movable means for shielding the area between said platens when the shielding means is in closed position, for preventing inadvertent insertion of an extremity such as the arm or hand of a workman between the platens during closure thereof, and with the safety device being mechanical and operative to positively stop closure of the platens when the shielding means is out of its closed position. The safety device takes the form of mechanical abutments adapted for holding coaction in connection with the relatively movable platens to prevent the closure thereof in the event that the shielding means is disposed in non-closed position.

United States Patent 1 Moslo [111 3,771,936 [451 Nov. 13, 1973 SAFETYDEVICE FOR MOLDING MACHINE [76] Inventor: Ernest P. Moslo, 12700 LakeAve., Lakewood, Ohio [22] Filed: May 12, 1971 [21.] Appl. No.: 142,472

[52] US. Cl 425/153, 425/DIG. 45 [51] Int. Cl B30b 15/00, B29f1/00, Fl6p3/12 [58] Field of Search 425/135, 136, 151,

425/152, 153, 154, DIG. 45; 18/30 CS, 30 CM [56] References Cited IUNITED STATES PATENTS 3,117,348 H1964 Rees 425/136 X 3,386,133 6/1968Weiner 425/153 2,415,462 2/1947 Cherry et a1... 425/DIG. 45 7 2,801,4428/1957 Moslo 425/DIG. 45

FOREIGN PATENTS OR APPLICATIONS 854.902 11/1960 Great Britain 425/1531,088,881 9/1954 France 425/151 Primary Examiner-J. Howard Flint, .Ir.Att0rneyBa1dwin, Egan, Walling & Fetzer [57] ABSTRACT A safety devicefor a machine mechanism having relatively movable pressure applyingoperating portions such as a molding machine having relatively movablemold platens, with movable means for shielding the area between saidplatens when the shielding means is in closed position, for preventinginadvertent insertion of an extremity such as the arm or hand of aworkman between the platens during closure thereof, and with the safetydevice being mechanical and operative to positively stop closure of theplatens when the shielding means is out of its closed position. Thesafety device takes the form of mechanical abutments adapted for holdingcoaction in connection with the relatively movable platens to preventthe closure thereof in the event that the shielding means is disposed innonclosed position. i

12 Claims, 11 Drawing Figures PAIENIEnNuv 13 ms 3371.936

SHEET 1 BF 4 v F|G.8 H69 JNVENTOR ERNEST P. MOSLO BY AT TO R EYSPATENTEUNDY 1 3 I975 3.771, 936

SHEET 2 BF 4 FIG.2

INVEN'TOR ERNEST P. MOSLO 6 I maa zToR 1% EYS PATENTEUHUV 13 I975 SHEETU 0F 4 I'NVENTOR ERNEST P. MOSLO BY W,

ATTO R N Y8 SAFETY DEVICE FOR MOLDING MACHINE This invention relates toimprovements in machine mechanisms and more particularly to a safetydevice for preventing the closure of relatively movable pressureapplying operating portions of the machine, such as for instance aplastic molding machine of the type having relatively movable platens.

BACKGROUND OF THE INVENTION In machines having relatively movableoperating members, such as for instance, plastic molding machines,wherein relatively movable mold supporting platens move from an openposition to a closed position and vice versa during closing and openingmovements of the molds, there is always the danger present that aworkman may have one of his extremities, such as a hand or an arm,extended between the operating memv bers (e.g. the relatively movableplatens) during closure thereof. This, of course, can result in seriousinjury to or severance of the workmans extremity. Various mechanismshave been proposed in the past for physically preventing a workman frominserting an extremity between the relatively movable operating membersduring closing thereof.

In U.S. Pat. No. 3,505,708 issued Apr. 14, 1970 to Ernest P. Moslo andentitled Fluid Power- Actuated Clamp For Molding Apparatus, there isdisclosed a fluid powered actuated clamp for a plastic molding apparatuswherein the present safety mechanism may be expeditiously utilized. Suchmolding apparatus may conventionally include sliding screening panelsor, shielding means which have to be moved by the workman to a closedposition, for shielding the space between the relatively movable platensduring closure thereof, so as to prevent the workman from inserting hishand or arm between the closing platens. Such mechanism conventionallymay have an electrical switch circuit on the machine so that unless theshielding means is in closed position so as toprevent to workmanfrominserting his arm into the space or area between the movable platens,the power toclose the platens cannot be applied thereto. However, itispossible that such switch circuit may fail, such as for instance by theswitch thereof remaining in a closed position even after the shieldingmeans is "opened. Thereafter of course the workman would be exposed tothe'danger of being able to close the platens while his arm or hand wasinserted between the relatively'movable platens when shielding means wasnot in closed position.

SUMMARY OF THE INVENTION The present invention provides a mechanicalsafety device, which may be used in conjunction with other safetydevices, such as the aforediscussed electrical circuit safety device,and which is operable to positively therefore permitting the moldplatens to close when the shielding panel is in closed position.However, when the shielding panel is in non-closed position, the movableabutment, being non-deactuated by the shielding panel, moves intoabutting coaction with the rack-like member and is operable to preventclosure of the'mold platens. The power circuit of the main actuator tothe movable platens has pressure relief means associated therewith, sothat when the mechanical safety device prevents closure of the platens,the power being applied to the main actuator is bypassed from the mainactuator, to prevent damage thereto.

Accordingly, an object of the invention is to provide a novel mechanicalsafety device for relatively movable pressure applying operator membersof a mechanism, so as to prevent closure of the operator members unlessa shielding means for the operator members has first been closed.

Another object of the invention is to provide a molding machine havingrelatively movable platens and wherein there is provided a movableshielding means that is operable when closed to normally prevent aworkman from inserting an extremity between the relatively movableplatens during closure thereof and wherein mechanical safety means ofthe aforedescribed type is provided in conjunction with'the machine forpreventing closure of the platens in the event that the shielding meansis not disposed in closed position.

" the abutment ba'r being automatically moved out of co-:

Another object of the invention is to provide a molding machine of theplastic injection type having a movable platen and a stationary platenfor supporting mold sections thereon, and with there being provided amov- -able safety shield which when in closed position is adapted toprevent a workman from inserting one of his extremities, such as an arm,between the closing platens, and wherein a rack member is attached tothe movable platen and an abutment bar is movably mounted to thestationary platen so that the abutment bar will move into abuttingcoaction with the rack to mechanically prevent closure of ,the movableplaten toward the stationary platen in the event that the. movableshield is not disposed in closed position, and with action with the rackwhen the shield is in closed posi-' tion, so as to permit closure of theplatens.

Other objects and advantages of the invention will be apparent from thefollowing description taken in con- 1 junction with th accompanyingdrawings wherein:

prevent a closure of relatively movable operator or platen members of apower machine mechanism, and as those of the moldihg'machine ofaforediscussed U.S. Pat. No. 3,505,708, unless a shielding panel or dooris in closed position. In the form illustrated, the safety devicecomprises a rack-like member which is attached to the movable platen ofthe molding machine andmoves therewith, and a movable abutment membermounted to the stationary platen of the machine. The shielding door orpanel has cam means thereon which is operable to deactuate the movableabutment from coaction with the rack when the shielding panel is inclosed position,

DESCRIPTION OF DRAWINGS FIG. 1' is a reduced size, side elevational viewof a molding machine embodying the invention;

FIG. 2 is an enlarged sectional view taken generally along the plane ofline 2-2 of FIG. 1 looking in the direction of the arrow;

FIG. 3 is a side elevational view taken generally along the plane ofline 3-3 of FIG. 2 looking in the direction of the arrows, andillustrating the shielding means on closed position, and the mechanicalsafety mechanism is in. deactuated condition.

FIG. 4 is a fragmentary, top plan view taken generally along the planeof line 44 of FIG. 3, looking in the direction of the arrows, andillustrating the mechanical safety mechanism of the invention;

FIG. 5 is an enlarged, side elevation view of the abutment bar of thesafety device, which is adapted for pivotal movement toward and awayfrom coaction with the rack member of the safety device;

FIG. 6 is an end elevational view taken generally along the plane of 66of FIG. 5, looking in the direction of the arrows;

FIG. 7 is a top plan view of the abutment bar of FIG.

FIG. 8 is an enlarged side elevational view of the movable blade memberwhich is assembled with the abutment bar of FIG. 5, for providing forsmooth movement of the rack of the safety device relative to theabutment bar, during opening movement of the platens;

FIG. 9'is an elevational view taken generally along the plane 99 of FIG.8 looking in the direction of the arrows;

FIG. 10 is an enlarged, fragmentary, side elevational view showing thecoaction of the locking abutment bar with the toothed rack, so as toprevent closure of the platens, when the shield of the machine is notpositioned in closed position during closing movement of the platens;the rearwardly swing position of the blade member in the active positionof the abutment bar is shown; and

FIG. 11 is an enlarged side elevational view of the cam on the shieldingmeans of the machine which deactuates the mechanical safety mechanism inthe closed condition of the shielding means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now again to thedrawings and particularly to FIG. 1, there is disclosed a moldingmachine of the horizontal plastic injection type embodying the presentinvention. The molding machine may comprise a base 10 which may be ofhollow construction for housing mechanism as necessary to operate themolding machine. The base may have a first support 12 mounted thereonadjacent one end thereof and a second support 14 in the form of astationary platen mounted on the base in longitudinally spaced relationto support 12.

Bars or rails 16 of cylindrical configuration in the embodimentillustrated, extend between supports 12 and 14, and may be securedthereto as by means of threaded nuts 18. Rails 16 provided supports onwhich is mounted a movable platen 20 which is adapted for movementtoward and away from the stationary platen l4. Mold sections 22, 22a(FIG. 1) may be secured as by means of conventional fasteners to therespective platen, and are adapted for mating relation upon closure ofthe platens and thus closure of the mold sections, to provide a moldcavity for receiving mold material therein.

Mounted adjacent the outer end of base 10 there may be provided aplastic injection mechanism 26 which may be of conventional type,including a screw or ram injector 28 for injecting the plastic materialinto the closed mold and via nozzle means 30. Power actuator mechanism32 is provided adapted for coacting with the movable platen 20 formoving the movable platen toward and away from the stationary platen 14and for clamping the mold sections tightly together during the moldingprocess. Reference may be had to aforementioned U.S. Pat. No. 3,505,708for a more detailed discussion of the operation of actuator 32 andmovable and stationary platens l4 and 20 in conjunction with injectionmechanism 26.

As shown in FIGS. 14, the molding machine is provided with screening orshielding means comprising in the embodiment illustrated movable panels34, 34a. Shielding panels 34, 34a may have flanged rollers 36 (FIGS. 2and 3) rotatably mounted thereon and as by means of stub axles 36a (FIG.2) which coact with tracks 38 extending between the supports 12 and 14,for guiding the movement of the shielding panels from open to closedposition and vice versa. Panel 34 is the panel that shields the volumeor area V (FIG. 1) between the relatively movable platens 20, 14 of themolding machine, and may be provided with a handle 40 (FIG. 3) which isadapted for manual manipulation by the machine operator, to open andclose the panel 34 in the process of obtaining entry to the spacebetween the molding platens 20, 14. Glass covered sight openings 41 maybe provided in panels 34, 34a.

As can best be seen in FIG. 3, panel 34. may be provided with anactuator 42 adjustably secured thereto, which is adapted to coact withan electrical switch mechanism 44 mounted on stationary platen 14 forclosing the switch mechanism 44 to permit the applica tion of power tothe main actuator mechanism 32 of the molding machine, when theshielding panel 34 is disposed in closed position, so that the movableplaten 20 and its associated mold section 22 can be moved toward thestationary platen 14 and its associated mold section 22a, to close themold sections during the molding operation. Movement of the shieldingpanel 34 to the left (with reference to FIG. 3) may deactuate the switch44 and cut off the power circuit to main actuator mechanism 32, so thatactuation of the actuator 32 to close the platens is not possible unlessand until switch 44 has been reactuated. However, as aforementioned, theswitch mechanism 44 could fail or become jammed, and the circuit to theactuator 32 for moving the movable platen 20 toward the stationaryplaten 14 would still be operative even though the shielding panel 34.

and its associated switch actuator 42 has moved away from closedposition, thus presenting a situation where an operator could extend hisarm into the space V between the plates and have an injury occur to theworkman upon closing of the platens.-

As can be seen in FIG, 2, these shielding panels may be provided on bothsides of the machine, with both sides being provided with theaforementioned safety switch means 44. However, the operator of amachine generally works from only one side thereof, and thus theopposite side is generally maintained in closed condition by theshielding panels unless maintainence or the like is occurring on themachine. Ordinarily, during ordinary molding operations, the machineoperator is working from the side of the machine illustrated in FIG. 1.The aforementioned generally closed panels on the opposite side of themachine are designated with like reference numbers as the first sidewith suffix prime added thereto.

In accordance with the present invention, safety mechanism 48 of amechanical type, is provided for positively preventing closure of therelatively movable platens in the event that the shielding door or panel34 is not in closed position, so that even if the safety switchmechanism 44 would happen to fail as aforediscussed, the movable platen20 could still not be moved toward the stationary platen 14. In theembodiment illustrated, this mechanical safety mechanism comprises aracklike member 50 having'a series of tooth abutments 52 laterallyspaced from one another along a portion of the lengthwise extent ofmember 50. Each tooth member 52, as can best be seen in FIG. 3,comprises'a generally vertical downstream abutment surface 54, asubstantially flat top surface 54a, and a sloping upstream surface 54b.Member 50 may be rigidly secured to the movable platen 20, as by meansof bolts 56 and is adapted to move linearaly with movement of themovable platen, toward and awayfrom the stationary platen 14. The distalor free end of rack 50 is received in an opening 58 in a support housing59 mounted as by means of bolts 59a to stationary platen 14.

Mounted on the housing 59 above opening 58 therethrough is abutmentmeans in the form of a drop bar 62 pivoted as at 64 to housing 59, forpivotal movement in a generally vertical plane. Abutment bar 62comprises an elongated member bifurcated as at 66 (FIG. 7) and havingdepending abutment shoulders or teeth 68 on the bifurcated portion 66.Each abutment shoulder 68 presents a generally vertical abutment surface68a which is adapted for abutting coaction with abutment surface 54 on aconfronting one of the teeth 52 of rack member 50, when the abutment baris disposed in downwardly pivoted, operative abutting coacting relationwith the rack 50, for positively preventing movement of the movableplaten 20 toward the stationary platen 14, and as shown for instance inFIG. 10. As will be seen, due to the location of pivotal axis 64 ofabutment bar 62, the bar tends to move downwardly toward the rack 50 dueto gravity.

The abutment bar may be provided with a roller member 70 (FIG. 2)projecting laterally therefrom, with roller member 70 being adapted forcamming coaction with a cam 72 on the shielding panel 34, when the panel34 is in closed position (FIG. 2). As'can best be seen in FIGS. 2 and 3,when the cam 72 engages the roller 70, theroller moving along thesloping top surface'70a of the cam, causes the abutment bar'62 to bepivoted upwardly, so that the abutment shoulders 68 on the abutment bar62 clear the teeth of rack 50. Accordingly, since the shoulders are outof interferring relation with the rack, the main actuator 32 on themolding machine can move the movable platen 20 and its associated moldsection 22 toward the stationary platen 14 and its associated moldsection 22a, to close the mold sections and thus provide the mold cavityfor the molding operation. However,'when the shielding panel 34 is notin closed position, then of course the weight of the abutment bar 62causes it to pivot downwardly about its pivotal axis 64 thereby causingthe shoulders 68 to mate with a confronting one of the teeth on theunderlying abutment rack 50, and mechanically'prevent-further movementof the movable'platen 20 toward the stationary platen l4.

The circuit to the main actuator 32 can be provided with relief means720 so that intheevent that abutting holding coaction occurs between theabutment bar and the rack 50, the power applied to the actuator 32,which may be for instance a hydraulic actuator, is bypassed to resvoir,so as to prevent injury or damage to the main actuator, and in a knownmanner.

The injection molding machine may be effectively used with greatplurality of sizes of mold sections 22, 22a so that of course manydifferent items can be produced on the machine. The safety mechanismwith the elongated rack 50 is such that it will operate effectively toprevent closure of the platens unless the shielding means 34 is inclosed condition, irrespective of the size of mold section on the platenfor production of the desired item. In other words the molds can bechanged on the machine without any necessity of adjusting the safetymechanism to accommodate a different size mold arrangement.

As can be best seen in FIGS. 5-10, the abutment bar 62 is provided witha blade member 73 which is a platelike article pivoted adjacent one ofthe corners thereof as at 73a to the distal end of the abutment bar 62,so that the blade can swing in a generally vertical plane within thebifurcated portion 66 of the abutment bar. The blade 73 may be providedwith a notched section 76 (FIG. 8) which is adapted for engagement withpin stop 79 extending across the bifurcated portion 66 of the abutmentbar 62, so as to limit clockwise (with reference to FIG. 10) pivotalmovement of the blade 73. In other words, blade 73 is freely swingablewithin the bifurcated portion 66 of the abutment bar 62, with gravitytending to cause downward swinging movement thereof about pivot 73a.

The purpose of the blade 73 is to provide for smooth movement of. therack 50 relative to the abutment bar 62 during opening movement of themold, or in other words, when the movable platen 20 is moving away fromthe stationary platen 14. As can be best seen in FIGS. 8 and 10, thewidth X of the blade 73 is such that it spans the distance betweenadjacent abutment teeth 52 on rack 50. Accordingly, in the event thatthe shielding panel 34 is moved from a closed to an open positiondisengaging cam 72 from roller 70 on the abutment bar, so that theabutment bar 62 swings downwardly, the blade 73, which when in itsdownwardly swing position and in engagement with stop 79 extendsslightly below abutment shoulders 68, will ride on the top surfaces 54of teeth 52 of rack 50 and will holdthe abutment bar 62 and itsassociated abutment shoulders 68 abovethe level of the tceth'on rack-50. As the movable platen 20 moves away from the stationary platen 14,the blade 73 rides smoothly alongthe top surfaces of the abutment teeth52 on the rack 50 while holding abutment shoulders 68 above the rackteeth, and thus provides for smooth linear movement of the rack relativeto the abutment bar during opening movement of the mold, and when theshielding panel 34 is in open position. It will be seen that the drag ofthe rack 50 on the underside 77 of the blade 73, holds the blade in agenerally vertical position, with stop 79 engaging notch 76 of the blade73.

As may be seen from FIG. 11, cam 72 may have vertically elongated slots82 through which are received fasteners 84 (FIG. 2), with such slotsproviding means for adjusting the position of the cam 72 on the innerside of shielding panel 34. In connection with shielding Surface 90 mayinclude oblique section 90a adapted for camming coaction with roller 88to urge shielding panel 34 into finalized closed position and provide aninitial resistance to opening movement of the shielding panel.

Cover housing 92 (FIGS. 1 and 3) may be secured to support housing 59 inalignment with opening 58 therethrough for receiving the distal end ofrack 50 during closing movement of the platens.

From the foregoing discussion and accompanying drawings it will be seenthat the invention provides a novel mechanical safety apparatus for amechanism having relatively movable, powered operating portions whichare openable and closeable with respect to one another, and whereininjury to a workman might occur if one or more of his extremities arepositioned between the movable operating portions when the portionsclose, and a safety mechanism which operates positively to preventclosure of the relatively movable operating portions of the mechanismunless a shielding means is first disposed in closed condition. Theshielding means is for the purpose of preventing insertion of a workmansextremity between the movable operating portions during closure thereof.The relatively movable operating portions may be, for instance theplatens of an injection molding machine, and the safety apparatus issuch that it operates effectively with a great plurality of differentsizes of mold sections for use with the platens of the machine.

The terms and expressions which have been used are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of any of thefeatures shown or described, or portions thereof, and it is recognizedthat various modifications are possible within the scope of theinvention claimed.

1 claim:

1. in a machine mechanism having a pair of relatively movable, spacedpressure applying operating portions, power means for causing openingand closing movement between said operating portions, means movable froman open position to a closed position and vice versa for screening whenin said closed position, the area between said operating portions toprevent inadvertent insertion of a workman s extremity between theoperating portions during dlosing movement thereof, mechanical safetymeans coacting with said operating portions operative to stop closingmovement of the latter unless said screening means is in said closedposition, said safety means comprising a toothed rack-like memberattached to one of said operating portions and a movable abutment membersupported by the other of said operating portions, the last mentionedmembers being adapted for abutting holding coaction upon closingmovement'of said operating portions when said screening means is innon-closed position, said movable abutment member including means forcoaction with means on said screening means when the latter is disposedin said closed position, for moving said abutment member to a deactuatedposition where it is maintained but of holding coaction with saidrack-like member so long as said screening means remains in said closedposition.

' 2. A mechanism in accordance with claim 1 wherein said movableabutment member comprises a drop bar pivotally mounted adjacent one endthereof to said other of said operating portions and having a dependingabutment tooth thereon for holding coaction with said toothed rack-likemember, to prevent closing movement of said operating portions when saidscreening means is in non-closed position.

3. A mechanism in accordance with claim 1 wherein the mechanism is alongitudinally operating molding machine, said operating portionscomprising a station ary platen and a movable platen, and said means onsaid screening means and on said abutment member comprising cammingmeans for lifting said abutment member'to a deactuated position whereinit is maintained out of holding coaction with said rack-like member whensaid screening means is in said closed position.

4. A mechanism in accordance with claim 1 wherein said operatingportions comprise a pair of relatively movable platens, said screeningmeans comprising a generally vertically oriented longitudinally slidabledoor so as to open and close accessibility to the area between saidplatens, and said means on said screening means comprising a cam mountedon the inner side of said door for coaction with said means on saidabutment member, for deactivating said safety means to permit movementof said platens toward closing position when said door is in closedposition, said means on said abutment member comprising a laterallydisposed roller for riding on said cam.

5. A mechanism in accordance wtih claim 1 wherein said mechanismcomprises an injection molding machine, said operating portionscomprising platens including a stationary, platen having means thereonfor mounting a mold section and a movable platen likewise having meansthereon for mounting a mold section for coaction with the firstmentioned mold section for defining a mold cavity, and said rack-likemember being secured to said movable platen for movement therewith andrelative to said stationary platen, said racklike member extendinglengthwise in the direction of said stationary platen with the teeththereof pointing upwardly, said abutment member comprising a drop barhaving depending abutment tooth means thereon for holding coactionwithconfronting of the teeth on said rack-like member in the active positionof said safety means, said bar being pivotally mounted adjacent one endthereof on said stationary platen for swinging movement in a generallyvertical plane.

6. A molding machine in accordance with claim 1 wherein said safetymeans includes means for coaction with said rack-like member forreducing the noise of return of the movable operating portion towardopen position when said screening means is disposed out of closedposition, said means for reducing noise when coacting with saidrack-like member being operable to maintain said abutment member out ofengagement with said rack-like member.

7. A mechanism in accordance with claim 6 wherein said abutment membercomprises a drop bar pivoted to said other operating portion, said meansfor reducing the noise of return including a plate pivoted to said dropbar, said plate when in a generally vertical position extending belowsaid drop bar for riding engagement with said rack-like member to liftsaid drop bar above the teeth of said rack-like member, said plate beingpivotal with respect to said rack-like member rearwardly during closingmovement of said operating portions to a position wherein it no longerextends below said drop bar.

8. A molding machine in accordance with claim wherein a support memberis eccentrically pivoted to said drop bar for movement in a generallyvertical plane co-planar with the plane of swinging movement of saiddrop bar, and extends downwardly from said drop bar when in actuatedposition, said support member being engageable by said rack-like memberon movement of said movable platen toward said stationary platen tocause rearward pivoting of said support member to deactuated position,said support member moving by gravity to said actuated condition whereinit extends downwardly below said drop bar and rides on said rack-likemember when said movable platen and attached rack-like member move awayfrom said stationary platen and said screening means is out of saidclosed position, and stop means on said drop bar for en'- gagement withsaid support member for limiting the pivotal movement of said supportmember in at least one pivotal direction.

9. A mechanism in accordance with claim 5 wherein the teeth of saidrack-like member are of buttress-like type spaced longitudinallytherealong with the vertical surface of each tooth being on thedownstream side thereof and the sloping face of each tooth being on theupstream side thereof, said generally vertical face being for abuttingcoaction with said drop bar when said safety means is in operativeposition to prevent closure of said operating portions of saidmechanism.

10. A mechanism in accordance with claim 9 wherein said tooth means ofsaid drop bar includes laterally spaced abutment shoulders thereonadapted for said abutting coaction with said vertical face when saiddrop bar is in said operative position.

11. A mechanism in accordance with claim 5 including a housing on saidstationary platen receiving said rack-like member therein upon movementof said movable platen toward said stationary platen.

12. A mechanism in accordance with claim 4 including means for coactionwith said door to resiliently urge said door into said closed positionand resiliently resist opening movement thereof.

1. In a machine mechanism having a pair of relatively movable, spacedpressure applying operating portions, power means for causing openingand closing movement between said operating portions, means movable froman open position to a closed position And vice versa for screening whenin said closed position, the area between said operating portions toprevent inadvertent insertion of a workman''s extremity between theoperating portions during dlosing movement thereof, mechanical safetymeans coacting with said operating portions operative to stop closingmovement of the latter unless said screening means is in said closedposition, said safety means comprising a toothed rack-like memberattached to one of said operating portions and a movable abutment membersupported by the other of said operating portions, the last mentionedmembers being adapted for abutting holding coaction upon closingmovement of said operating portions when said screening means is innon-closed position, said movable abutment member including means forcoaction with means on said screening means when the latter is disposedin said closed position, for moving said abutment member to a deactuatedposition where it is maintained out of holding coaction with saidrack-like member so long as said screening means remains in said closedposition.
 2. A mechanism in accordance with claim 1 wherein said movableabutment member comprises a drop bar pivotally mounted adjacent one endthereof to said other of said operating portions and having a dependingabutment tooth thereon for holding coaction with said toothed rack-likemember, to prevent closing movement of said operating portions when saidscreening means is in non-closed position.
 3. A mechanism in accordancewith claim 1 wherein the mechanism is a longitudinally operating moldingmachine, said operating portions comprising a stationary platen and amovable platen, and said means on said screening means and on saidabutment member comprising camming means for lifting said abutmentmember to a deactuated position wherein it is maintained out of holdingcoaction with said rack-like member when said screening means is in saidclosed position.
 4. A mechanism in accordance with claim 1 wherein saidoperating portions comprise a pair of relatively movable platens, saidscreening means comprising a generally vertically orientedlongitudinally slidable door so as to open and close accessibility tothe area between said platens, and said means on said screening meanscomprising a cam mounted on the inner side of said door for coactionwith said means on said abutment member, for deactivating said safetymeans to permit movement of said platens toward closing position whensaid door is in closed position, said means on said abutment membercomprising a laterally disposed roller for riding on said cam.
 5. Amechanism in accordance wtih claim 1 wherein said mechanism comprises aninjection molding machine, said operating portions comprising platensincluding a stationary platen having means thereon for mounting a moldsection and a movable platen likewise having means thereon for mountinga mold section for coaction with the first mentioned mold section fordefining a mold cavity, and said rack-like member being secured to saidmovable platen for movement therewith and relative to said stationaryplaten, said rack-like member extending lengthwise in the direction ofsaid stationary platen with the teeth thereof pointing upwardly, saidabutment member comprising a drop bar having depending abutment toothmeans thereon for holding coaction with confronting of the teeth on saidrack-like member in the active position of said safety means, said barbeing pivotally mounted adjacent one end thereof on said stationaryplaten for swinging movement in a generally vertical plane.
 6. A moldingmachine in accordance with claim 1 wherein said safety means includesmeans for coaction with said rack-like member for reducing the noise ofreturn of the movable operating portion toward open position when saidscreening means is disposed out of closed position, said means forreducing noise when coacting with said rack-like member being operableto maintain said abutment member out of engagement with said rack-likemember.
 7. A mechanism in accordance with claim 6 wherein said abutmentmember comprises a drop bar pivoted to said other operating portion,said means for reducing the noise of return including a plate pivoted tosaid drop bar, said plate when in a generally vertical positionextending below said drop bar for riding engagement with said rack-likemember to lift said drop bar above the teeth of said rack-like member,said plate being pivotal with respect to said rack-like memberrearwardly during closing movement of said operating portions to aposition wherein it no longer extends below said drop bar.
 8. A moldingmachine in accordance with claim 5 wherein a support member iseccentrically pivoted to said drop bar for movement in a generallyvertical plane co-planar with the plane of swinging movement of saiddrop bar, and extends downwardly from said drop bar when in actuatedposition, said support member being engageable by said rack-like memberon movement of said movable platen toward said stationary platen tocause rearward pivoting of said support member to deactuated position,said support member moving by gravity to said actuated condition whereinit extends downwardly below said drop bar and rides on said rack-likemember when said movable platen and attached rack-like member move awayfrom said stationary platen and said screening means is out of saidclosed position, and stop means on said drop bar for engagement withsaid support member for limiting the pivotal movement of said supportmember in at least one pivotal direction.
 9. A mechanism in accordancewith claim 5 wherein the teeth of said rack-like member are ofbuttress-like type spaced longitudinally therealong with the verticalsurface of each tooth being on the downstream side thereof and thesloping face of each tooth being on the upstream side thereof, saidgenerally vertical face being for abutting coaction with said drop barwhen said safety means is in operative position to prevent closure ofsaid operating portions of said mechanism.
 10. A mechanism in accordancewith claim 9 wherein said tooth means of said drop bar includeslaterally spaced abutment shoulders thereon adapted for said abuttingcoaction with said vertical face when said drop bar is in said operativeposition.
 11. A mechanism in accordance with claim 5 including a housingon said stationary platen receiving said rack-like member therein uponmovement of said movable platen toward said stationary platen.
 12. Amechanism in accordance with claim 4 including means for coaction withsaid door to resiliently urge said door into said closed position andresiliently resist opening movement thereof.